R. v. E.M.W., 2010 NSCA 73 para 56 is a good source for the foundational (but often ignored) principal that an accused's evidence ought not to be rejected just because Crown witnesses are believed. The Court held:
The defence is neutered in the starting gate regardless of how the accused presents or testifies. The accused has not really been disbelieved. He has been marginalized. So it is impermissible to reject the accused's testimony solely as a consequence of believing the Crown witnesses. The trier of fact should address both whether the Crown witnesses are believed and whether the accused is disbelieved. This is the rationale for W.(D.)'s first question.